U.S. patent number 8,636,403 [Application Number 12/522,666] was granted by the patent office on 2014-01-28 for timepiece component and method for making same.
This patent grant is currently assigned to Patek Philippe sa Geneve. The grantee listed for this patent is Sylvain Jeanneret, Frederic Maier, Stephane Von Gunten. Invention is credited to Sylvain Jeanneret, Frederic Maier, Stephane Von Gunten.
United States Patent |
8,636,403 |
Maier , et al. |
January 28, 2014 |
Timepiece component and method for making same
Abstract
A timepiece component, such as a balance, an oscillating mass or
a wheel, having a structure made according to a micro-manufacturing
technique, such as the DRIE technique. The component has at least
one member formed in or at the periphery of the structure and made
of a material different from that of the structure. This member is
typically metal and is formed by electro-forming using a cavity of
the structure as a mold.
Inventors: |
Maier; Frederic (Neuchatel,
CH), Von Gunten; Stephane (Corcelles, CH),
Jeanneret; Sylvain (Colombier, CH) |
Applicant: |
Name |
City |
State |
Country |
Type |
Maier; Frederic
Von Gunten; Stephane
Jeanneret; Sylvain |
Neuchatel
Corcelles
Colombier |
N/A
N/A
N/A |
CH
CH
CH |
|
|
Assignee: |
Patek Philippe sa Geneve
(Geneva, CH)
|
Family
ID: |
39944070 |
Appl.
No.: |
12/522,666 |
Filed: |
February 15, 2008 |
PCT
Filed: |
February 15, 2008 |
PCT No.: |
PCT/IB2008/000345 |
371(c)(1),(2),(4) Date: |
November 04, 2009 |
PCT
Pub. No.: |
WO2008/135817 |
PCT
Pub. Date: |
November 13, 2008 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20100054089 A1 |
Mar 4, 2010 |
|
Foreign Application Priority Data
Current U.S.
Class: |
368/169; 368/171;
368/322; 368/148 |
Current CPC
Class: |
G04B
5/165 (20130101); G04B 13/026 (20130101); B81C
99/0095 (20130101); G04F 7/08 (20130101); G04D
3/0069 (20130101); G04B 17/063 (20130101); G04B
13/022 (20130101); B81C 99/0085 (20130101); G04D
3/00 (20130101); G04B 13/02 (20130101); Y10T
29/49579 (20150115); Y10T 29/49581 (20150115); B81B
2201/035 (20130101) |
Current International
Class: |
G04B
17/00 (20060101); G04B 31/00 (20060101); G04B
25/02 (20060101) |
Field of
Search: |
;368/124,127,168,169,322-326,171 ;29/896.31 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
|
|
|
339868 |
|
Jul 1959 |
|
CH |
|
17517/71 D |
|
Feb 1975 |
|
CH |
|
0 732 635 |
|
Sep 1996 |
|
EP |
|
0 957 414 |
|
Nov 1999 |
|
EP |
|
1 655 642 |
|
May 2006 |
|
EP |
|
1 850 193 |
|
Oct 2007 |
|
EP |
|
1 275 357 |
|
Nov 1961 |
|
FR |
|
Other References
Machine translations of EP732635, EP1655642, FR1275357, CH339868.
cited by examiner .
International Search Report in PCT/IB2008/000345, Mar. 5, 2009.
cited by applicant .
Debbie G. Jones et al., Fabrication of Ultra Thick Ferromagnetic
Structures in Silicon, Proceeding os IMECE04, 2004 ASME
International Mechanical Engineering Congress and Exposition, Nov.
13-20, 2004, Anaheim, CA, IMECE2004-61909, pp. 25-28. cited by
applicant.
|
Primary Examiner: Miska; Vit W
Attorney, Agent or Firm: Bacon & Thomas, PLLC
Claims
The invention claimed is:
1. A timepiece component comprising a structure made of a first
material and having a periphery, and at least one element made of a
second material different from the first material, wherein the
first material is silicon and said element is metallic and
electroformed in the structure or at the periphery of the structure
to form a single piece with the structure.
2. The timepiece component as claimed in claim 1, wherein the
structure includes a cavity and said element fills the cavity.
3. The timepiece component as claimed in claim 1, wherein said
element is located in the same plane and has the same height as the
structure.
4. The timepiece component as claimed claim 1, wherein said element
protrudes beyond the plane of the structure.
5. The timepiece component as claimed in claim 1, wherein said
component comprises a balance, and said element is located at the
periphery of the structure to increase the inertia/mass ratio of
the balance.
6. The timepiece component as claimed in claim 1, wherein said
component comprises an oscillating mass for an automatic winding
mechanism, and said element is located at the periphery of the
structure to increase the unbalance/mass ratio of the oscillating
mass.
7. The timepiece component as claimed in claim 1, said component
adapted to be driven onto a support member, wherein said element
comprises a central hole intended to receive such support
member.
8. The timepiece component as claimed in claim 4, said element
defining a pinion, a cam or a chronograph heart-piece outside the
plane of the structure.
9. The timepiece component as claimed in claim 7, comprising a
balance, an oscillating mass or a wheel.
Description
FIELD OF INVENTION
The present invention relates to a timepiece component and its
method of manufacture.
More particularly, the present invention relates to a timepiece
component formed using a micro-manufacturing technique.
BACKGROUND
Some timepiece components, i.e., balance springs and wheels, are
manufactured from silicon nowadays. Silicon is useful owing to its
lightness, its resiliency, its non-magnetic properties and for its
ability to be machined by micro-manufacturing techniques, in
particular by the deep reactive-ion etching (DRIE) technique.
However, silicon does have some disadvantages: it is fragile, in
other words it does not have any plasticity, which makes it
difficult for example to attach a silicon wheel to an axle.
Moreover, its extreme lightness does not permit components such as
a balance or oscillating mass, which must have sufficient inertia
or unbalance, to be formed completely from silicon and to be formed
with small dimensions.
Materials other than silicon, themselves also able to be machined
by micro-manufacturing techniques, and whose use could be
envisioned for manufacturing timepiece components, have the same
disadvantages. These materials are, in particular, diamond, quartz,
glass and silicon carbide.
SUMMARY
The present invention aims to enable the micro-manufacturing of
timepiece components for applications which have heretofore not
been envisioned owing to the said disadvantages of the materials
used.
To this end, there is provided a timepiece component comprising a
structure which can be formed by a micro-manufacturing technique,
characterised in that it further comprises at least one element
formed in or at the periphery of the structure and formed of a
material different from that of the structure.
The said element can modify the mechanical properties of the
component to make this component usable in a given application
whilst maintaining the advantages of the material used to form the
structure. This element can be used, for example, to increase the
inertia/mass ratio of a balance or the unbalance/mass ratio of an
oscillating mass, or to absorb locally some of the stresses
generated by the driving of an axle. It will be noted that the said
element is formed in or at the periphery of the structure and is
not added thereto. The entire timepiece component can thus be
manufactured by micro-manufacturing techniques, i.e., techniques
permitting precision in the order of microns. The said element thus
does not impair the manufacturing precision of the component.
The present invention also proposes a method of manufacturing a
timepiece component, comprising a step of forming a structure by a
micro-manufacturing technique, characterised in that it further
comprises a step consisting of forming at least one element in or
at the periphery of the structure, said element being of a material
different from that of the structure, such that the final timepiece
component comprises said structure and said element.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become
clear upon reading the following detailed description of several
embodiments of the invention with reference to the accompanying
drawings, in which:
FIGS. 1 and 2 are respectively a top, plan view and an axial,
cross-sectional view of a balance in accordance with the
invention;
FIG. 3 is a perspective view of an oscillating mass in accordance
with the invention;
FIGS. 4 and 5 are respectively a top, plan view and an axial,
cross-sectional view of a wheel in accordance with the
invention;
FIG. 6 is a perspective view of an oscillating mass in accordance
with another embodiment;
FIG. 7 schematically shows a method of manufacturing a timepiece
component such as those shown in FIGS. 1 to 3;
FIG. 8 schematically shows a method of manufacturing a timepiece
component such as that shown in FIGS. 4 and 5;
FIG. 9 schematically shows a method of manufacturing a wheel and a
pinion; and
FIG. 10 schematically shows a method of manufacturing the
oscillating mass shown in FIG. 6.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE DISCLOSURE
With reference to FIG. 1, a balance 1 in accordance with the
invention for a timepiece movement comprises a main silicon
structure 2 and metal elements 3. The silicon structure 2 comprises
an annular central part 4, arms 5 which extend radially from the
central part 4 and, at the end of these arms 5, closed contours 6
which define through-going cavities 7, e.g., in the form of a bean.
The cavities 7 are filled by the metal elements 3, respectively,
and form separate rim segments with these elements 3.
The metal elements 3 are formed of a material having a higher
density than silicon. They thus make the periphery of the balance 1
heavier and increase the inertia of the balance to achieve a
desired inertia. The inner part of the balance 1, formed by the
central part 4 and the arms 5, is extremely lightweight owing to
the fact that it is formed of silicon and that it is largely
hollow. Since the inner part of a balance contributes less to the
inertia than the peripheral part, a large inertia/mass ratio can be
achieved. Thus, with the same inertia as a traditional metal
balance, the total mass of the balance 1 is smaller. This is
advantageous, in particular, in that it decreases the friction on
the pivots of the axle of the balance in the bearings.
In an alternative embodiment, the rim could be continuous, i.e.,
the rim segments 3, 6 could be in contact with each other.
The metal elements 3 are typically formed of gold; however, they
could be formed of another metal, in particular another metal
having a high density such as platinum.
The silicon structure 2 and the metal elements 3 are formed by
micro-manufacturing or micro-forming techniques. The balance 1 can
thus be manufactured with a high degree of precision. Its inertia
will thus be precise, which will facilitate its pairing with a
balance spring to obtain a desired frequency for the balance spring
regulator device of the timepiece movement. An example of the
manufacturing process of the balance 1 will be described
hereinafter.
As shown in FIG. 2, the metal elements 3 are in the same plane as
the silicon structure 2 and have the same constant height as the
latter. In this manner, the metal elements 3 can take up a large
volume without increasing the height of the balance 1. However, as
an alternative, the metal elements 3 could extend beyond the
cavities 7 in order, e.g., to reinforce the holding of these
elements 3 in the silicon structure 2.
The balance 1 can be mounted on its axle by placing, as shown in
FIGS. 1 and 2, an annular piece 8 formed of a soft metal material,
such as gold, into the central part 4 of the silicon structure 2
and by driving the axle of the balance, designated by the reference
numeral 9, into this annular piece 8. The annular piece 8 is sized
so as to be deformed when the axle 9 is driven in and thus to
absorb some of the stresses exerted by the axle 9 to prevent the
silicon from breaking. In FIG. 2, the reference numerals 10 and 11
designate the large roller and the small roller of the escapement
mechanism.
Referring to FIG. 3, an oscillating mass 12 in accordance with the
invention for an automatic winding mechanism of a timepiece
comprises a main silicon structure 13 and metal elements 14. The
silicon structure 13 comprises a thin main part 15 comprising a
hole 16 for mounting the oscillating mass 12 on an axle or ball
bearing, and a thicker peripheral part 17. The oscillating mass 12
can be mounted on its axle or its ball bearing in the same manner
as the balance 1, i.e., using an intermediate piece formed of a
soft material.
The metal elements 14 fill respective through-going cavities 18 in
the thick peripheral part 17. The metal elements 14 are formed of a
material having a higher density than silicon, e.g., gold or
platinum. They thus make the periphery of the oscillating mass 12
heavier and increase its unbalance to obtain a desired unbalance.
The inner part 15 of the oscillating mass 12 is thus extremely
lightweight since it is formed of silicon and is thin. This inner
part 15 could be hollowed out to be made even more lightweight.
Since the inner part of an oscillating mass contributes less to the
unbalance than the peripheral part, a large unbalance/mass ratio
can be achieved. Thus, with the same unbalance as a traditional
metal oscillating mass, the total mass of the oscillating mass 10
is smaller. This is advantageous, in particular, in that it
decreases friction. An example of the manufacturing process of the
oscillating mass 12 will be described hereinafter.
Referring to FIGS. 4 and 5, a toothed wheel 20 in accordance with
the invention for a timepiece mechanism comprises a main silicon
structure 21 and an annular metal element 22 formed in a central
through-going cavity in the structure 21. An axle can pass through
the central hole 23 in the element 22. The diameter of this central
hole 23 is selected to be less than the diameter in the axle so as
to allow the wheel 20 to be mounted on the axle by driving. Since
the material of which the element 22 is formed, e.g., gold or
nickel, has a high degree of deformability, in contrast to silicon,
some of the stresses exerted by the axle will be absorbed by the
element 22, which will prevent the silicon from breaking. An
element such as element 22 thus constitutes a means of locally
absorbing the driving stresses, without impairing the manufacturing
precision of the component since, as will be seen hereinafter, the
element 22 can be formed by a micro-manufacturing or micro-forming
technique.
It will be seen that a metal element such as element 22 shown in
FIGS. 4, 5 could also be formed in the central cavity of the
silicon structure of the balance 1 or of the oscillating mass 12
and could replace the annular piece 8.
Furthermore, in the illustrated example, the element 22 has the
same height as the silicon structure 21. In an alternative
embodiment, the element 22 could have a greater height than the
structure 21 in order to define, for example, a pinion which is
co-axial to the wheel 20 and is fixedly attached thereto. An
exemplified method for manufacturing this alternative embodiment
will be described hereinafter.
FIG. 6 shows an oscillating mass 25 in accordance with an
alternative embodiment of the invention. This oscillating mass 25
differs from the oscillating mass 12 illustrated in FIG. 3 by
virtue of the fact that the metal elements 14 are replaced by a
metal element 26 formed on a peripheral surface 27 of the main
silicon structure, designated by the reference numeral 28. The
element 26 has a circular arc shape and extends over the whole
length and height of the surface 27. In order to reinforce the
connection between the element 26 and the silicon structure 28,
anchoring protrusions embedded in the element 26 can be provided on
the peripheral surface 27. An exemplified method of manufacturing
the oscillating mass 25 will be described hereinafter. In a manner
similar to the element 26, a circular metal element could be formed
on a peripheral surface of a silicon structure, either continuously
or non-continuously, to manufacture a balance for example.
FIG. 7 schematically shows an exemplified method of manufacturing
the components illustrated in FIGS. 1, 2 and 3. In a first step
(FIG. 7a), the silicon structure 30 of the component, with its
cavity or cavities 31, is formed by deep reactive-ion etching
(DRIE). For reasons of simplicity, the structure 30 is illustrated
as having only a single height. In the case of the balance 1, a
single DRIE step is necessary. In the case of the oscillating mass
12, two DRIE steps are carried out to produce the thin part 15 and
the thick part 17. In a second step (FIG. 7b), a first layer of
photosensitive resin 32, a metal layer 33 and a second layer of
photosensitive resin 34 are successively formed on a support plate
35 formed of silicon or pyrex for example. In a third step (FIG.
7c), the support plate 35 with its layers 32, 33, 34 and the
silicon structure 30 are adhesively joined together, the
photosensitive resin layer 34 being used as the adhesive. In a
fourth step (FIG. 7d), the exposed portions of the photosensitive
resin 34, i.e., the portions facing the cavities 31, are removed by
a photolithographic method using the silicon structure 30 as a
mask. In a fifth step (FIG. 7e), metal is formed in the cavities 31
by electroforming (galvanic growth) from the exposed portions of
the metal layer 33 and by using the silicon walls of the cavities
31 as moulds. Then, the plate 35 and the layers 32, 33, 34 are
removed (FIG. 7f) leaving the silicon structure 30 with the metal
elements 37 formed in the initial cavities 31, and a levelling
operation is carried out, for example by lapping, to provide the
elements 37 with the same height as the structure 30.
During the fourth and fifth steps, some areas 36 can be masked in a
manner known per se so as not to be subjected to electroforming.
These areas 36 are, for example, empty spaces between silicon parts
which have been left during the DRIE process to form bars keeping
the structure 30 attached to other structures formed simultaneously
in a single plate. These bars are broken at the end of the
manufacturing process to separate the components.
The support plate 35 and the silicon structure 30 can be joined
together (third step; FIG. 7c) in a different manner from that
described above, e.g., by thermo-compression of the metal layer 33
against the structure 30 (in this case, the photosensitive resin
layer 34 is omitted) or by replacing the photosensitive resin layer
34 by dried liquid silicon oxide.
More details regarding the method described above can be found in
the article by Debbie G. Jones and Albert P. Pisano entitled
"Fabrication of ultra thick ferromagnetic structures in silicon",
Proceedings of IMECE04, 2004 ASME International Mechanical
Engineering Congress and Exposition, 13-20 Nov. 2004, Anaheim,
Calif., USA, in which a similar method is described for
manufacturing ferromagnetic structures in silicon.
FIG. 8 schematically shows how a central annular metal element such
as element 22 illustrated in FIGS. 4 and 5 can be formed. FIG. 8
shows more precisely how this central element can be formed
simultaneously with peripheral elements. The first four steps are
similar to the steps of FIGS. 7a to 7d respectively. A fifth step,
shown in FIG. 8a, consists of filling the cavities 31 of the
silicon structure 30 with a photosensitive resin such as an SU-8
resin. A sixth step (FIG. 8b) consists of removing this SU-8 resin
by a photolithographic method, except in a central part of the
central cavity 38 corresponding to the hole in the central metal
element. A seventh step (FIG. 8c) consists of forming metal in the
cavities 31, 38. In the central cavity 38, this metal is formed
only around the remaining portion 39 of the SU-8 resin. Then, the
support plate 35 with its layers 32, 33, 34 is removed (FIG. 8d)
and the remaining portion 39 of the SU-8 resin is removed (FIG.
8e). One or more peripheral metal elements 40, which are used for
example to increase the inertia of the component, and a central
annular element 41, enabling the driving of an axle for example,
are thus obtained.
FIG. 9 schematically shows an exemplified method of manufacturing a
component comprising an annular central metal element such as
element 22 illustrated in FIGS. 4 and 5 but having a greater height
to define a pinion. The first four steps are similar to the steps
of FIGS. 7a to 7d respectively. A fifth step, shown in FIG. 9a,
consists of forming photosensitive SU-8 resin 50 in the central
cavity of the silicon structure 30 and beyond this cavity, on the
upper surface of the silicon structure 30. A sixth step (FIG. 9b)
consists of photo-structuring the photosensitive resin 50 so as to
define, with the silicon structure 30, a cavity 51 having the form
of the annular central element and of its pinion. A seventh step
(FIG. 9c) consists of electroforming metal in the cavity 51. The
support plate 35 with its layers 32, 33, 34 and the photosensitive
resin 50 are then removed (FIGS. 9d and 9e), leaving a silicon
structure 30 and an annular metal element 22a formed in the
structure 30 and extending beyond this structure 30 to define a
pinion 22b. A central hole 22c passes through the combination 22a,
22b, into which hole an axle can be driven. In alternative
embodiments, the annular element 22a could define elements other
than a pinion, e.g., a cam or a chronograph heart-piece.
FIG. 10 schematically shows how the metal element 26 of the
oscillating mass 25 illustrated in FIG. 6 can be formed. In first
steps (FIG. 10a), the silicon structure 28 is formed by two DRIE
steps, a support plate 35 with successive layers of photosensitive
resin 32, of metal 33 and of photosensitive resin 34 is joined to
the structure 28, the portion of the photosensitive resin 34
located outside the structure 28 is removed to expose the metal
layer 33 and then a portion of photosensitive SU-8 resin 42 is
formed outside the structure 28, in a similar manner to the portion
39 of FIG. 8, to form a cavity 43 with the silicon structure 28. In
a following step (FIG. 10b), metal is electroformed in the cavity
43. In following steps (FIG. 10c), the plate 35 with its layers 32,
33, 34 and then the resin 42 are removed.
In all of the methods described above, the silicon structure is
generally covered by a silicon oxide layer prior to the
electroforming step. This layer is the result of the natural
oxidation of the silicon. Its thickness can be increased by placing
the silicon structure in an oxidation oven prior to electroforming.
The silicon oxide in fact improves some mechanical properties of
the silicon such as the coefficient of friction or mechanical
strength. Other coatings can also be deposited on the silicon
structure if desired. It will thus be understood that the metal
elements are not necessarily in direct contact with the silicon but
can be in contact with silicon oxide walls or with a particular
coating.
In addition to a high level of precision, it will be appreciated
that the methods of manufacturing the components in accordance with
the invention described above enable a large number of components
to be formed simultaneously from a single plate.
Although the invention has been described above for silicon
structures, it could be applied to other materials which can be
machined by micro-manufacturing techniques, in particular by the
DRIE technique, such as diamond, quartz, glass or silicon
carbide.
* * * * *